Vignetting is
a defect that darkens the corners of an image due to light falloff around
the perimeter of the lens. Chromatic aberration appears
as a color fringe along the edges of objects, caused by the lens
focusing on different colors of light in different planes.

Some lenses exhibit different defects at certain focal lengths,
f‑stops, and focus distances. With the Lens Correction filter, you
can specify the combination of settings used to make the image.

Correct lens distortion and adjust
perspective

The
Lens Correction filter fixes common lens flaws such as barrel and
pincushion distortion, vignetting, and chromatic aberration. The
filter works only with 8‑ and 16‑bit-per-channel images in RGB or
Grayscale mode.

You can also use the filter to rotate an image
or fix image perspective caused by vertical or horizontal camera
tilt. The filter’s image grid makes these adjustments easier and
more accurate than using the Transform command.

Automatically correct image perspective
and lens flaws

Using lens profiles, the default Auto Correction
option quickly and accurately fixes distortion. For proper automatic
correction, Photoshop requires Exif metadata that identifies the
camera and lens that created the image, and a matching lens profile
on your system.

Choose Filter > Lens Correction.

Set the following options:

Correction

Select the problems you want to fix. If corrections undesirably extend
or contract the image beyond original dimensions, select Auto Scale Image.

The
Edge menu specifies how to handle blank areas that result from pincushion, rotation,
or perspective corrections. You can fill blank areas with transparency
or a color, or you can extend the edge pixels of the image.

Select a matching profile. By default, Photoshop displays only profiles that match the camera and lens used to create the image. (The camera model does not have to match perfectly.) Photoshop also automatically selects a matching sub-profile for the selected lens based on focal length, f-stop and focus distance. To change the automatic selection, right-click the current lens profile, and select a different sub-profile.

Manually correct image perspective
and lens flaws

You
can apply manual correction alone or use it to refine automatic
lens correction.

Choose
Filter > Lens Correction.

In the upper-right corner of the dialog box, click the
Custom tab.

(Optional) Choose a preset list of settings from the Settings menu. Lens Default uses settings that you previously saved for the camera, lens, focal length, f‑stop, and focus distance used to create the image. Previous Conversion uses the settings used in your last lens correction. Any group of custom settings you saved are listed at the bottom of the menu. (See Save settings and set camera and lens defaults.)

Set any of the following options to correct your image.

Remove Distortion

Corrects lens barrel or pincushion distortion. Move the slider
to straighten horizontal and vertical lines that bend either away
from or toward the center of the image. You can also use the Remove
Distortion tool to
make this correction. Drag toward the center of the image to correct
for barrel distortion and toward the edge of the image to correct
for pincushion distortion. To compensate for any blank image edges
that result, adjust the Edge option on the Auto Correction tab.

Fix Fringe settings

Compensate for fringing by adjusting the size of one color channel relative to another.

Бележка:

Zoom in on the image preview to get a closer view of the fringing as you make the correction.

Vignette Amount

Sets the amount of lightening or darkening along the edges of an image. Corrects images that have darkened corners caused by lens faults or improper lens shading.

Бележка:

You can also apply vignetting for a creative effect.

Vignette Midpoint

Specifies the width of area affected by the Amount slider. Specify
a lower number to affect more of the image. Specify a higher number
to restrict the effect to the edges of the image.

Vertical Perspective

Corrects image perspective caused by tilting the camera up
or down. Makes vertical lines in an image parallel.

Horizontal Perspective

Corrects image perspective, making horizontal lines parallel.

Angle

Rotates the image to correct for camera tilt or to make adjustments after correcting perspective. You can also use the Straighten tool to make this correction. Drag along a line in the image that you want to make vertical or horizontal.

Adjusts the image scale up or down. The image pixel dimensions
aren’t changed. The main use is to remove blank areas of the image
caused by pincushion, rotation, or perspective corrections. Scaling
up effectively results in cropping the image and interpolating up
to the original pixel dimensions.

Adjust the Lens Correction preview
and grid

Adjust the preview magnification and grid
lines to better judge the necessary amount of correction.

To change the image preview magnification,
use the Zoom tool or the zoom controls in the lower left side of
the preview image.

To move the image in the preview window, select the Hand
tool and drag in the image preview.

To use the grid, select Show Grid at the bottom of the
dialog box. Use the Size control to adjust the grid spacing and
the Color control to change the color of the grid. You can move
the grid to line it up with your image using the Move Grid tool .

Save settings and set camera and
lens defaults

You can save the settings in the Lens Correction
dialog box to reuse with other images made with the same camera,
lens, and focal length. Photoshop saves both Auto Correction settings
and Custom settings for distortion, chromatic aberration, and vignetting.
Perspective correction settings are not saved because they typically
vary from one image to another.

You can save and reuse settings
in two ways:

Manually save and load settings. Set
options in the dialog box, and then choose Save Settings from the
Settings menu . To
use the saved settings, choose them from the Settings menu. (If
you save settings outside the default folder, they don’t appear
in the menu; use the Load Settings command to access them.)

Set a lens default. If your image has EXIF metadata for the
camera, lens, focal length, and f‑stop, you can save the current
settings as a lens default. To save the settings, click the Set
Lens Default button. When you correct an image that matches the
camera, lens, focal length, and f‑stop, the Lens Default option becomes
available in the Settings menu. This option is not available if
your image doesn’t have EXIF metadata.

Reduce image noise and JPEG artifacts

Image
noise appears as random extraneous pixels that aren’t part of the
image detail. Noise can be caused by photographing with a high ISO
setting on a digital camera, underexposure, or shooting in a dark
area with a long shutter speed. Low‑end consumer cameras usually
exhibit more image noise than high‑end cameras. Scanned images may
have image noise caused by the scanning sensor. Often, the film’s
grain pattern appears in the scanned image.

Image noise can
appear in two forms: luminance (grayscale) noise, which makes an
image look grainy or patchy, and color noise, which is usually visible
as colored artifacts in the image.

Luminance noise may be
more pronounced in one channel of the image, usually the blue channel.
You can adjust the noise for each channel separately in Advanced
mode. Before opening the filter, examine each channel in your image separately
to see if noise is prevalent in one channel. You preserve more image detail
by correcting one channel rather than making an overall correction
to all channels.

Choose
Filter > Noise > Reduce Noise.

Zoom in on the preview image to get a better view of
image noise.

Set options:

Strength

Controls the amount of luminance noise reduction applied
to all image channels.

Preserve Details

Preserves edges and image details such as hair or texture objects.
A value of 100 preserves the most image detail, but reduces luminance noise
the least. Balance the Strength and Preserve Details controls to
fine‑tune noise reduction.

Reduce Color Noise

Removes random color pixels. A higher value reduces more
color noise.

Sharpen Details

Sharpens the image. Removing noise reduces image sharpness.
Use the sharpening control in the dialog box or use one of the other Photoshop
sharpening filters later to restore sharpness.

If luminance noise is more prevalent in one or two color
channels, click the Advanced button and then choose the color channel
from the Channel menu. Use the Strength and Preserve Details controls
to reduce noise in that channel.